To improve fuel economy of an engine in a vehicle, the vehicle is controlled by calculating a target drive force based on a vehicle speed and an accelerator pedal opening and calculating a speed ratio and a target engine torque in accordance with an optimal fuel consumption line.
The engine combusts fuel by taking in air. Since an air density is low, for example, in the case of traveling in highland, an actual engine torque may become lower than a target engine torque, the vehicle may not be controlled in accordance with the optimal fuel consumption line and fuel economy may be deteriorated even if the target engine torque is calculated in accordance with the optimal fuel consumption line and the engine is controlled to achieve the target engine torque.
Contrary to this, in an invention described in JP2001-47892A, a target engine torque is calculated based on an air density and a reduction of an actual engine torque due to the air density is suppressed by controlling an engine based on the calculated target engine torque.